[PATCH] iio: adc: imx93: fix a signedness bug in imx93_adc_read_raw()

[PATCH] iio: adc: imx93: fix a signedness bug in imx93_adc_read_raw()

[Dan Carpenter]

The problem is these lines:

	ret = vref_uv = regulator_get_voltage(adc->vref);
	if (ret < 0)

The "ret" variable is type long and "vref_uv" is u32 so that means
the condition can never be true on a 64bit system.  A negative error
code from regulator_get_voltage() would be cast to a high positive
u32 value and then remain a high positive value when cast to a long.

The "ret" variable only ever stores ints so it should be declared as
an int.  We can delete the "vref_uv" variable and use "ret" directly.

Fixes: 7d02296ac8b8 ("iio: adc: add imx93 adc support")
Signed-off-by: Dan Carpenter <error27@gmail.com>
---
 drivers/iio/adc/imx93_adc.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/adc/imx93_adc.c b/drivers/iio/adc/imx93_adc.c
index d8de8284e13d..8c68f0cd48f2 100644
--- a/drivers/iio/adc/imx93_adc.c
+++ b/drivers/iio/adc/imx93_adc.c
@@ -236,8 +236,7 @@ static int imx93_adc_read_raw(struct iio_dev *indio_dev,
 {
 	struct imx93_adc *adc = iio_priv(indio_dev);
 	struct device *dev = adc->dev;
-	long ret;
-	u32 vref_uv;
+	int ret;
 
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
@@ -253,10 +252,10 @@ static int imx93_adc_read_raw(struct iio_dev *indio_dev,
 		return IIO_VAL_INT;
 
 	case IIO_CHAN_INFO_SCALE:
-		ret = vref_uv = regulator_get_voltage(adc->vref);
+		ret = regulator_get_voltage(adc->vref);
 		if (ret < 0)
 			return ret;
-		*val = vref_uv / 1000;
+		*val = ret / 1000;
 		*val2 = 12;
 		return IIO_VAL_FRACTIONAL_LOG2;
 
-- 
2.35.1

RE: [PATCH] iio: adc: imx93: fix a signedness bug in imx93_adc_read_raw()

[Bough Chen]

> -----Original Message-----
> From: Dan Carpenter <error27@gmail.com>
> Sent: 2023年2月14日 23:48
> To: Bough Chen <haibo.chen@nxp.com>
> Cc: Jonathan Cameron <jic23@kernel.org>; Lars-Peter Clausen
> <lars@metafoo.de>; Shawn Guo <shawnguo@kernel.org>; Sascha Hauer
> <s.hauer@pengutronix.de>; Pengutronix Kernel Team
> <kernel@pengutronix.de>; Fabio Estevam <festevam@gmail.com>; dl-linux-imx
> <linux-imx@nxp.com>; linux-iio@vger.kernel.org;
> kernel-janitors@vger.kernel.org
> Subject: [PATCH] iio: adc: imx93: fix a signedness bug in imx93_adc_read_raw()
> 
> The problem is these lines:
> 
> 	ret = vref_uv = regulator_get_voltage(adc->vref);
> 	if (ret < 0)
> 
> The "ret" variable is type long and "vref_uv" is u32 so that means the condition
> can never be true on a 64bit system.  A negative error code from
> regulator_get_voltage() would be cast to a high positive
> u32 value and then remain a high positive value when cast to a long.
> 
> The "ret" variable only ever stores ints so it should be declared as an int.  We
> can delete the "vref_uv" variable and use "ret" directly.

Thanks for the catching!

Reviewed-by: Haibo Chen <haibo.chen@nxp.com>

Best Regards
Haibo Chen
> 
> Fixes: 7d02296ac8b8 ("iio: adc: add imx93 adc support")
> Signed-off-by: Dan Carpenter <error27@gmail.com>
> ---
>  drivers/iio/adc/imx93_adc.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/adc/imx93_adc.c b/drivers/iio/adc/imx93_adc.c index
> d8de8284e13d..8c68f0cd48f2 100644
> --- a/drivers/iio/adc/imx93_adc.c
> +++ b/drivers/iio/adc/imx93_adc.c
> @@ -236,8 +236,7 @@ static int imx93_adc_read_raw(struct iio_dev
> *indio_dev,  {
>  	struct imx93_adc *adc = iio_priv(indio_dev);
>  	struct device *dev = adc->dev;
> -	long ret;
> -	u32 vref_uv;
> +	int ret;
> 
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
> @@ -253,10 +252,10 @@ static int imx93_adc_read_raw(struct iio_dev
> *indio_dev,
>  		return IIO_VAL_INT;
> 
>  	case IIO_CHAN_INFO_SCALE:
> -		ret = vref_uv = regulator_get_voltage(adc->vref);
> +		ret = regulator_get_voltage(adc->vref);
>  		if (ret < 0)
>  			return ret;
> -		*val = vref_uv / 1000;
> +		*val = ret / 1000;
>  		*val2 = 12;
>  		return IIO_VAL_FRACTIONAL_LOG2;
> 
> --
> 2.35.1

Re: [PATCH] iio: adc: imx93: fix a signedness bug in imx93_adc_read_raw()

[Jonathan Cameron]

On Wed, 15 Feb 2023 02:16:40 +0000
Bough Chen <haibo.chen@nxp.com> wrote:

> > -----Original Message-----
> > From: Dan Carpenter <error27@gmail.com>
> > Sent: 2023年2月14日 23:48
> > To: Bough Chen <haibo.chen@nxp.com>
> > Cc: Jonathan Cameron <jic23@kernel.org>; Lars-Peter Clausen
> > <lars@metafoo.de>; Shawn Guo <shawnguo@kernel.org>; Sascha Hauer
> > <s.hauer@pengutronix.de>; Pengutronix Kernel Team
> > <kernel@pengutronix.de>; Fabio Estevam <festevam@gmail.com>; dl-linux-imx
> > <linux-imx@nxp.com>; linux-iio@vger.kernel.org;
> > kernel-janitors@vger.kernel.org
> > Subject: [PATCH] iio: adc: imx93: fix a signedness bug in imx93_adc_read_raw()
> > 
> > The problem is these lines:
> > 
> > 	ret = vref_uv = regulator_get_voltage(adc->vref);
> > 	if (ret < 0)
> > 
> > The "ret" variable is type long and "vref_uv" is u32 so that means the condition
> > can never be true on a 64bit system.  A negative error code from
> > regulator_get_voltage() would be cast to a high positive
> > u32 value and then remain a high positive value when cast to a long.
> > 
> > The "ret" variable only ever stores ints so it should be declared as an int.  We
> > can delete the "vref_uv" variable and use "ret" directly.  
> 
> Thanks for the catching!
> 
> Reviewed-by: Haibo Chen <haibo.chen@nxp.com>

Applied to the fixes-togreg branch of iio.git.

Thanks

Jonathan

> 
> Best Regards
> Haibo Chen
> > 
> > Fixes: 7d02296ac8b8 ("iio: adc: add imx93 adc support")
> > Signed-off-by: Dan Carpenter <error27@gmail.com>
> > ---
> >  drivers/iio/adc/imx93_adc.c | 7 +++----
> >  1 file changed, 3 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/iio/adc/imx93_adc.c b/drivers/iio/adc/imx93_adc.c index
> > d8de8284e13d..8c68f0cd48f2 100644
> > --- a/drivers/iio/adc/imx93_adc.c
> > +++ b/drivers/iio/adc/imx93_adc.c
> > @@ -236,8 +236,7 @@ static int imx93_adc_read_raw(struct iio_dev
> > *indio_dev,  {
> >  	struct imx93_adc *adc = iio_priv(indio_dev);
> >  	struct device *dev = adc->dev;
> > -	long ret;
> > -	u32 vref_uv;
> > +	int ret;
> > 
> >  	switch (mask) {
> >  	case IIO_CHAN_INFO_RAW:
> > @@ -253,10 +252,10 @@ static int imx93_adc_read_raw(struct iio_dev
> > *indio_dev,
> >  		return IIO_VAL_INT;
> > 
> >  	case IIO_CHAN_INFO_SCALE:
> > -		ret = vref_uv = regulator_get_voltage(adc->vref);
> > +		ret = regulator_get_voltage(adc->vref);
> >  		if (ret < 0)
> >  			return ret;
> > -		*val = vref_uv / 1000;
> > +		*val = ret / 1000;
> >  		*val2 = 12;
> >  		return IIO_VAL_FRACTIONAL_LOG2;
> > 
> > --
> > 2.35.1  
>